#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/module.h>

#define MAX_SYMBOL_LEN 64
static char symbol[MAX_SYMBOL_LEN] = "security_inode_mkdir";
// int security_inode_mkdir(struct inode *dir, struct dentry *dentry, umode_t
// mode);

/* For each probe you need to allocate a kprobe structure */
static struct kprobe kp = {
    .symbol_name = symbol,
};

/* kprobe pre_handler: called just before the probed instruction is executed */
// 通过传递参数的寄存器获取传入的参数。
static int handler_pre(struct kprobe* p, struct pt_regs* regs)
{
    struct dentry* dentry = NULL;
    dentry                = (struct dentry*)regs->si;
    pr_info("regs->si = %s\n", dentry->d_name.name);
    /* A dump_stack() here will give a stack backtrace */
    return 0;
}

/* kprobe post_handler: called after the probed instruction is executed */
static void handler_post(struct kprobe* p, struct pt_regs* regs,
                         unsigned long flags)
{
}

/*
 * fault_handler: this is called if an exception is generated for any
 * instruction within the pre- or post-handler, or when Kprobes
 * single-steps the probed instruction.
 */
static int handler_fault(struct kprobe* p, struct pt_regs* regs, int trapnr)
{
    return 0;
}

static int __init kprobe_init(void)
{
    int ret;
    kp.pre_handler   = handler_pre;
    kp.post_handler  = handler_post;
    kp.fault_handler = handler_fault;

    ret = register_kprobe(&kp);
    if (ret < 0) {
        pr_err("register_kprobe failed, returned %d\n", ret);
        return ret;
    }
    pr_info("Planted kprobe at %p\n", kp.addr);
    return 0;
}

static void __exit kprobe_exit(void)
{
    unregister_kprobe(&kp);
    pr_info("kprobe at %p unregistered\n", kp.addr);
}

module_init(kprobe_init) module_exit(kprobe_exit) MODULE_LICENSE("GPL");